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Wednesday, September 28, 2011

Crews scale Washington Monument checking for earthquake damage

A team of engineers recently rappelled down the sides of the Washington Monument looking for damage caused by a rare earthquake that hit the East Coast in August. Crews exited the iconic monument from windows at the 500-foot level and scaled to the top to do a very close visual inspection. They were conducting an inventory of cracks sustained during the earthquake to determine whether those cracks could, in the next couple of years, grow.

The heaviest damage appears to be concentrated at the very top of the monument, in what is called the pyramidion, where large cracks of up to 1-1/4 inch wide developed through stone and mortar joints, according to officials with the National Mall and Memorial Parks. Daylight is visible through some of the cracks, and rain water has gotten into the monument, which could cause further damage.

The difficult-access rappelling team scaled the outside of the structure to get a closer look. They installed climbing ropes and safety lines on all four sides, then clipped onto those lines. They climbed up the pyramidion and then descended the length of the monument looking for exterior damage.

The Washington Monument, built between 1848 and 1884, is 555 feet tall. Its walls, 15-feet thick at the base and 18-inches at the top, are composed primarily of white marble blocks, according to the Park Service.

On a journey to Washington, D.C. with Discovery Student Adventures, which famous landmark would you most like to explore?